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            <div><h4 class="title">
                <a name="asio.overview.networking.iostreams"></a><a class="link" href="iostreams.html"
                                                                    title="Socket Iostreams">Socket Iostreams</a>
            </h4></div>
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    <p>
        Asio includes classes that implement iostreams on top of sockets. These
        hide away the complexities associated with endpoint resolution, protocol
        independence, etc. To create a connection one might simply write:
    </p>
    <pre class="programlisting"><span class="identifier">ip</span><span class="special">::</span><span
            class="identifier">tcp</span><span class="special">::</span><span class="identifier">iostream</span> <span
            class="identifier">stream</span><span class="special">(</span><span
            class="string">"www.boost.org"</span><span class="special">,</span> <span class="string">"http"</span><span
            class="special">);</span>
<span class="keyword">if</span> <span class="special">(!</span><span class="identifier">stream</span><span
                class="special">)</span>
<span class="special">{</span>
  <span class="comment">// Can't connect.</span>
<span class="special">}</span>
</pre>
    <p>
        The iostream class can also be used in conjunction with an acceptor to
        create simple servers. For example:
    </p>
    <pre class="programlisting"><span class="identifier">io_context</span> <span class="identifier">ioc</span><span
            class="special">;</span>

<span class="identifier">ip</span><span class="special">::</span><span class="identifier">tcp</span><span
                class="special">::</span><span class="identifier">endpoint</span> <span
                class="identifier">endpoint</span><span class="special">(</span><span class="identifier">tcp</span><span
                class="special">::</span><span class="identifier">v4</span><span class="special">(),</span> <span
                class="number">80</span><span class="special">);</span>
<span class="identifier">ip</span><span class="special">::</span><span class="identifier">tcp</span><span
                class="special">::</span><span class="identifier">acceptor</span> <span
                class="identifier">acceptor</span><span class="special">(</span><span class="identifier">ios</span><span
                class="special">,</span> <span class="identifier">endpoint</span><span class="special">);</span>

<span class="keyword">for</span> <span class="special">(;;)</span>
<span class="special">{</span>
  <span class="identifier">ip</span><span class="special">::</span><span class="identifier">tcp</span><span
                class="special">::</span><span class="identifier">iostream</span> <span class="identifier">stream</span><span
                class="special">;</span>
  <span class="identifier">acceptor</span><span class="special">.</span><span class="identifier">accept</span><span
                class="special">(</span><span class="identifier">stream</span><span class="special">.</span><span
                class="identifier">socket</span><span class="special">());</span>
  <span class="special">...</span>
<span class="special">}</span>
</pre>
    <p>
        Timeouts may be set by calling <code class="computeroutput"><span class="identifier">expires_at</span><span
            class="special">()</span></code> or <code class="computeroutput"><span
            class="identifier">expires_from_now</span><span class="special">()</span></code> to establish a deadline.
        Any socket operations
        that occur past the deadline will put the iostream into a "bad"
        state.
    </p>
    <p>
        For example, a simple client program like this:
    </p>
    <pre class="programlisting"><span class="identifier">ip</span><span class="special">::</span><span
            class="identifier">tcp</span><span class="special">::</span><span class="identifier">iostream</span> <span
            class="identifier">stream</span><span class="special">;</span>
<span class="identifier">stream</span><span class="special">.</span><span
                class="identifier">expires_from_now</span><span class="special">(</span><span
                class="identifier">boost</span><span class="special">::</span><span class="identifier">posix_time</span><span
                class="special">::</span><span class="identifier">seconds</span><span class="special">(</span><span
                class="number">60</span><span class="special">));</span>
<span class="identifier">stream</span><span class="special">.</span><span class="identifier">connect</span><span
                class="special">(</span><span class="string">"www.boost.org"</span><span class="special">,</span> <span
                class="string">"http"</span><span class="special">);</span>
<span class="identifier">stream</span> <span class="special">&lt;&lt;</span> <span class="string">"GET /LICENSE_1_0.txt HTTP/1.0\r\n"</span><span
                class="special">;</span>
<span class="identifier">stream</span> <span class="special">&lt;&lt;</span> <span class="string">"Host: www.boost.org\r\n"</span><span
                class="special">;</span>
<span class="identifier">stream</span> <span class="special">&lt;&lt;</span> <span
                class="string">"Accept: */*\r\n"</span><span class="special">;</span>
<span class="identifier">stream</span> <span class="special">&lt;&lt;</span> <span class="string">"Connection: close\r\n\r\n"</span><span
                class="special">;</span>
<span class="identifier">stream</span><span class="special">.</span><span class="identifier">flush</span><span
                class="special">();</span>
<span class="identifier">std</span><span class="special">::</span><span class="identifier">cout</span> <span
                class="special">&lt;&lt;</span> <span class="identifier">stream</span><span
                class="special">.</span><span class="identifier">rdbuf</span><span class="special">();</span>
</pre>
    <p>
        will fail if all the socket operations combined take longer than 60 seconds.
    </p>
    <p>
        If an error does occur, the iostream's <code class="computeroutput"><span class="identifier">error</span><span
            class="special">()</span></code> member function may be used to retrieve
        the error code from the most recent system call:
    </p>
    <pre class="programlisting"><span class="keyword">if</span> <span class="special">(!</span><span class="identifier">stream</span><span
            class="special">)</span>
<span class="special">{</span>
  <span class="identifier">std</span><span class="special">::</span><span class="identifier">cout</span> <span
                class="special">&lt;&lt;</span> <span class="string">"Error: "</span> <span
                class="special">&lt;&lt;</span> <span class="identifier">stream</span><span
                class="special">.</span><span class="identifier">error</span><span class="special">().</span><span
                class="identifier">message</span><span class="special">()</span> <span
                class="special">&lt;&lt;</span> <span class="string">"\n"</span><span class="special">;</span>
<span class="special">}</span>
</pre>
    <h6>
        <a name="asio.overview.networking.iostreams.h0"></a>
        <span><a name="asio.overview.networking.iostreams.see_also"></a></span><a class="link"
                                                                                  href="iostreams.html#asio.overview.networking.iostreams.see_also">See
        Also</a>
    </h6>
    <p>
        <a class="link" href="../../reference/ip__tcp/iostream.html" title="ip::tcp::iostream">ip::tcp::iostream</a>,
        <a class="link" href="../../reference/basic_socket_iostream.html" title="basic_socket_iostream">basic_socket_iostream</a>,
        <a class="link" href="../../examples/cpp03_examples.html#asio.examples.cpp03_examples.iostreams">iostreams
            examples</a>.
    </p>
    <h6>
        <a name="asio.overview.networking.iostreams.h1"></a>
        <span><a name="asio.overview.networking.iostreams.notes"></a></span><a class="link"
                                                                               href="iostreams.html#asio.overview.networking.iostreams.notes">Notes</a>
    </h6>
    <p>
        These iostream templates only support <code class="computeroutput"><span class="keyword">char</span></code>,
        not <code class="computeroutput"><span class="keyword">wchar_t</span></code>, and do not perform
        any code conversion.
    </p>
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